--- - |2+ Objective In 2010, the State Insurance Regulatory Authority (SIRA), which governs the regulatory functions of workers’ compensation insurance (WCI) and compulsory third‐party insurance (CTP) within NSW, implemented evidence‐based clinical guidelines to improve psychologists’ practice. The aims of this study were to determine (a) whether this initiative has reduced claims costs and improved injured patient outcomes and (b) whether it has resulted in psychologists using evidence‐based practice. Method The first phase involved quantitatively determining a time‐range sample of WCI administrative records of patients with a musculoskeletal injury (n = 26,254) and musculoskeletal injury with a secondary psychological injury (n = 238). The second and third phases involved a qualitative content analysis of case‐level files belonging to individuals who had suffered a musculoskeletal injury with a secondary psychological injury under WCI (Phase 2) (n = 12) and CTP (Phase 3) (n = 9). Results The quantitative component revealed that the total claims costs and return to work timeframes for injured patients suffering from musculoskeletal injury with a secondary psychological injury remained unchanged following the implementation of the clinical guidelines. However, this contrasted with a significant increase of these measures for injured workers with only a musculoskeletal injury. The qualitative content analysis in Phases 2 and 3 of the study showed that psychologists’ application of treatment guidelines was suboptimal. Conclusion The implementation of the 2010 clinical guidelines for psychologists has led to beneficial outcomes for patients injured under the SIRA insurance frameworks; however, greater adherence by psychologists and strategies to improve the adoption of these guidelines are warranted. - Australian Psychologist, EarlyView.